<template>
  <div class="swiper-container" ref="imageSwiper">
    <div class="swiper-wrapper">
      <!-- v-for in undefined是不会报错的,它什么也不做 -->
      <div class="swiper-slide" 
      v-for="(image, index) in imageList" 
      :key="image.id">
        <img
          @click="changeDefault(index)"
          :src="image.imgUrl"
          :class="{ active: defaultIndex === index }"
        />
      </div>
    </div>
    <div class="swiper-button-next"></div>
    <div class="swiper-button-prev"></div>
  </div>
</template>

<script>

  import Swiper from 'swiper'
  export default {
    name: "ImageList",
    data(){
      return{
        defaultIndex:0
      }
    },
    props:['imageList'],
    methods:{
      // 点击切换图片边框颜色
      changeDefault(index){
        this.defaultIndex = index;

        // 通知兄弟组件zoom, 切换图片
      this.$bus.$emit("changeDefaultIndex", index);
      }
    },
    watch: {
      imageList: {
        immediate:true,  //这里加immediate没任何意义，只是为了让两遍代码保持一致
        handler(newVal, oldVal) {
          // this.$nextTick 等待页面最近一次更新完成后执行回调
          this.$nextTick(() => {
            new Swiper(this.$refs.imageSwiper, {
                // 如果需要前进后退按钮
                navigation: {
                  nextEl: ".swiper-button-next",
                  prevEl: ".swiper-button-prev",
                },
                // 同时显示多少张
                slidesPerView:3,
                // 每此切换多少张
                slidesPerGroup:2
            });
          });
        },
      },
    },
}
</script>

<style lang="less" scoped>
  .swiper-container {
    height: 56px;
    width: 412px;
    box-sizing: border-box;
    padding: 0 12px;

    .swiper-slide {
      width: 56px;
      height: 56px;

      img {
        width: 100%;
        height: 100%;
        border: 1px solid #ccc;
        padding: 2px;
        width: 50px;
        height: 50px;
        display: block;

        &.active {
          border: 2px solid #f60;
          padding: 1px;
        }

        // &:hover {
        //   border: 2px solid #f60;
        //   padding: 1px;
        // }
      }
    }

    .swiper-button-next {
      left: auto;
      right: 0;
    }

    .swiper-button-prev {
      left: 0;
      right: auto;
    }

    .swiper-button-next,
    .swiper-button-prev {
      box-sizing: border-box;
      width: 12px;
      height: 56px;
      background: rgb(235, 235, 235);
      border: 1px solid rgb(204, 204, 204);
      top: 0;
      margin-top: 0;
      &::after {
        font-size: 12px;
      }
    }
  }
</style>